Why do people often vote against their own interests?

[Drew Westen] uses the following exchange from the first presidential debate between Al Gore and George Bush in 2000 to illustrate the perils of trying to explain to voters what will make them better off:

Gore: "Under the governor's plan, if you kept the same fee for service that you have now under Medicare, your premiums would go up by between 18% and 47%, and that is the study of the Congressional plan that he's modelled his proposal on by the Medicare actuaries."

Bush: "Look, this is a man who has great numbers. He talks about numbers.

"I'm beginning to think not only did he invent the internet, but he invented the calculator. It's fuzzy math. It's trying to scare people in the voting booth."

Mr Gore was talking sense and Mr Bush nonsense - but Mr Bush won the debate. With statistics, the voters just hear a patronising policy wonk, and switch off.

For Mr Westen, stories always trump statistics, which means the politician with the best stories is going to win: "One of the fallacies that politicians often have on the Left is that things are obvious, when they are not obvious.

"Obama's administration made a tremendous mistake by not immediately branding the economic collapse that we had just had as the Republicans' Depression, caused by the Bush administration's ideology of unregulated greed. The result is that now people blame him."